CN100424948C - On-site cross-linked polyethylene welding cable joint technology - Google Patents

Abstract

The invention relates to a cross-linked polyethylene welded cable joint, in particular to a method for using a cross-linked polyethylene welded cable joint with a voltage above 35KV, in particular to a process method for performing cross-linked polyethylene welded cable joints on site. Its characteristics are: it adopts the same heatable and cross-linked polyethylene material as the cable insulation body (4), heats it to a cross-linked molten state above the softening temperature, and enters the tubular shape from the side of the tubular former (6) under pressure. Around the inner semiconductive layer (7) outside the cable conductor (5) of the two cable heads fixed in the former (6) and connected, it is welded together with the insulating body (4) at the end of the XLPE cable , and then cross-linked under the cross-linking temperature and pressure to make qualified cable joints. When the crosslinked polyethylene welding cable joint material is heated and enters the tubular former (6), it is in an uncrosslinked molten state, and its temperature is 120-130°C. When the cross-linked polyethylene welding cable joint material is heated and enters the tubular former (6), the pressure is not lower than 2.0Mpa. The cross-linking temperature after the melt of the cross-linked polyethylene welding cable joint material is welded together with the insulating body (4) at the end of the cable is 180-250°C.

Description

On-site cross-linked polyethylene welding cable joint technology

technical field

The invention relates to a cross-linked polyethylene welded cable joint, in particular to a method for using a cross-linked polyethylene welded cable joint with a voltage above 35KV, in particular to a process method for performing cross-linked polyethylene welded cable joints on site.

Background technique

The self-adhesive tape wrapping method used in XLPE cable joints in the 1970s has the disadvantage that the gap between the tapes is likely to cause electrical breakdown; the XLPE cable joint developed in the 1980s uses a cross-linkable polyethylene tape to wrap the heating mold. Plastic method, but the polyethylene tape is easy to absorb dust, and impurities are brought into the connector, which is easy to cause defects, and air bubbles in the connector are unavoidable. At present, many countries in the world use large-diameter compact integral prefabricated joints. After the connected cables are processed, the diameter of the prefabricated parts is expanded to exceed the diameter of the cable sheath, and the conductors are crimped on any section of the cable. , and then move the prefabricated part to the middle, pull out the expansion sleeve, adjust the prefabricated part to the specified position, and process the insulating outer shield and protective shell to complete the joint action. The treatment of the semi-conductive layer of the cable closely combined with it in the installation of this joint is a key process, which requires more human factors for on-site installation. It is inevitable that the fracture treatment of the semi-conductive layer is not neat enough, the slope is not uniform and smooth, and the semi-conductive layer coated The body of the glue and the cable may not be fastened together, and it is difficult to control the semi-conductive particles from being brought into the insulating joint; the prefabricated expanded expansion tube has slightly sharp corners or convex particles, which will crush the joint during expansion; When the prefabricated joint is made, the length of the outer sheath of the cable that is broken is twice as long as that of other forms of joints, and the sealing and mechanical level of the cable body cannot be achieved when it is restored. The patent disclosed in Japan, in 1994, JP 11-234838 adopts extrusion injection molding and cross-linking method to manufacture cross-linked polyethylene cable joint, which is a new method until the mid-nineties. However, due to the long production cycle of this kind of joint, three joints in one circuit need to be produced for one month, which is long in time, low in efficiency, waste of manpower and material resources, and is difficult to popularize and apply. We solve the problem of long production cycle of extrusion injection molding and cross-linking manufacturing cable joints.

Contents of the invention

The purpose of the present invention is to provide a simple construction, low cost, safe and reliable, easy to use, on-site cross-linked polyethylene welding cross-linked cable joint process method. The object of the present invention is achieved like this: it comprises outer sheath, aluminum sheath, outer semiconductive layer, insulating body, cable conductor, tubular former, inner semiconductive layer, add insulating body, fastening ring (9) , fastening bolts, pins, nut connectors, T-shaped half-molds, extruders, extrusion machines. It adopts the same heatable cross-linked polyethylene material as the cable insulation body, heats it to a cross-linked molten state above the softening temperature, enters the tubular former from the side of the tubular former, and distributes it evenly on the fixed and connected parts. Around the inner semiconductive layer outside the two good cable conductors; welded together with the insulating body at the end of the cross-linked polyethylene cable, and then cross-linked under cross-linking temperature and pressure to make a cable joint. When the cross-linked polyethylene welding cable joint material is heated into the tubular former, it is in an uncross-linked molten state, and its temperature is 120-130°C. When the XLPE fusion splicing cable joint material is heated into the tubular former, the pressure is not lower than 2.0MPa. The crosslinking temperature of the XLPE fusion cable joint material melt and the insulation body at the end of the cable is 180-250°C. The manufacturing process steps of cross-linked polyethylene fusion splicing cable joints include: stripping off a certain length of the outer semiconducting layer, insulating body, inner semiconducting layer and inner winding tape at the ends of the two cable joints to be connected, and connecting the exposed cables Conductor, inner winding tape and inner semi-conductive layer, process and clean the insulating surface of the cable end, buckle the tubular former on the insulating body and clamp it; then heat the barrel of the plastic extrusion machine, and put in the same amount as the cable insulating body The XLPE cable material that can be heated and cross-linked, and the extrusion machine is started to extrude the molten cross-linked polyethylene material. When the extruded cable material melt is continuous and transparent, the temperature of the extrusion machine is controlled At a constant temperature of 120°C, install the tubular former that has clamped the two cable ends to be welded on the extruder, and heat the tubular former and the T-shaped half-mold to 120°C; The polyethylene cable material is pressed into the tubular former, and the pressure is maintained when the pressure reaches 2.0MPa. After the injected cable material is full, the tubular former and its contents are pressurized and heated to 180°C, and kept at a constant temperature for 2 hours. , then heated to 250°C, constant temperature for 3 hours, 130°C for 2 hours, cooled the tubular former and its contents to room temperature with nitrogen, opened the tubular former and removed it, and repaired the exterior of the cable joint properly The outer semiconductive layer of the cable. The length of the outer semiconductive layer of each cable end is removed from 80 to 200mm, the length of the insulating body is removed from 60 to 180mm, and the length of the inner semiconductive layer is removed from 40 to 160mm. The advantages of the present invention are: simple on-site construction, low cost, safe and reliable, simple and convenient operation and use of equipment, short time and high efficiency, conforming to GB hall 11017-2002 <rated voltage 110kV above to 500kv XLPE insulated power cables and accessories > and IEC60840: 1999 < rated voltage 30kV (Um = 36kV) to 150kV (Um = 170kV) extruded insulated power cables and accessories > test methods and requirements, IEC62067: 2001 < rated voltage 150kV (Um = 170kV) to 500kV (Um=550kV) Test methods and requirements for extruded insulated power cables and accessories>Requirements.

Description of drawings

Fig. 1 is a schematic diagram of the structural principle of the present invention; Fig. 2 is a schematic diagram of the structural principle of the tubular former of the present invention; Fig. 3 is a schematic diagram of the sectional structure of the tubular former of the present invention; Fig. 4 is a schematic diagram of the tubular former, extruder, and extrusion injection machine of the present invention Schematic diagram of the box principle. The outer sheath is made of cross-linked polyethylene material, the outer semi-conductive layer and the inner semi-conductive layer are made of a mixture of cross-linked polyethylene and carbon powder, and the insulating body is made of cross-linked polyethylene material.

Detailed ways

First, buckle the two T-shaped mold halves 13 on the insulating body, and adjust the fastening ring 9, the fastening bolt 10, the pin 11, and the nut connector 12 to achieve a state of proper tightness. The cross-linked polyethylene raw material in the extruder 14 is melted and extruded into the extruder 15, and the extruder presses the uncross-linked cross-linked polyethylene cable material in the molten state into the tubular former 6. Adopt the same heatable and cross-linked polyethylene material as the cable insulation body 4, heat it to a cross-linked molten state above the softening temperature, and enter the two fixed wires in the tubular former 6 from the side of the tubular former 6 through pressurization. Around the inner semiconductive layer 7 outside the cable conductor 5 that has been connected to the cable head, it is welded together with the insulating body 4 at the end of the cross-linked polyethylene cable, and then cross-linked under the cross-linking temperature and pressure to make a qualified cable connectors. When the cross-linked polyethylene welding cable joint material is heated and enters the tubular former 6, it is in an uncross-linked molten state, and its temperature is 120-130°C. When the cross-linked polyethylene welding cable joint material is heated and enters the tubular former 6, it is under a pressure not lower than 2.0 MPa. The cross-linking temperature after the melt of the cross-linked polyethylene welding cable joint material is welded together with the insulating body 4 at the end of the cable is 180-250°C. The manufacturing process steps of cross-linked polyethylene fusion spliced cable joints include: stripping off a certain length of the outer semiconductive layer 3, the insulating body 4, the inner semiconductive layer 7 and the inner winding tape at the ends of the two cable joints to be connected. Exposed cable conductor 5, inner winding tape and inner semiconductive layer 7, process and clean the insulating surface of the cable end, buckle the tubular former 6 on the insulating body 4 and clamp it; temperature, drop into the same heatable and cross-linked cross-linked polyethylene cable material as the cable insulation body 4, and start the extruder 15 to extrude. When the extruded cable material melt is continuous and transparent, the extruder 15 The temperature is controlled at a constant temperature of 120°C, and the tubular former 6 that has clamped the two cable heads to be welded is installed on the extruder 15, heated to 120°C, and the uncrosslinked cross-linked polyethylene in the molten state is Press the cable material into the tubular former 6, and keep the pressure when the pressure reaches 2.0 MPa. After the injected cable material is full, pressurize and heat the tubular former 6 and its contents to 180°C, and keep the temperature constant for 2 hours. Then heat it to 250°C, keep the temperature constant for 3 hours, and keep the temperature at 130°C for 2 hours. After cooling the tubular former 6 and its contents to room temperature with nitrogen, open the tubular former 6 and remove it. After proper treatment of the outside of the cable joint, Repair the outer semi-conductive layer of the cable 3. The length of the outer semiconductive layer 3 of each cable end is removed by 80-200mm, the length of the insulating body 4 is removed by 60-180mm, and the length of the inner semiconductive layer 7 is removed by 40-160mm. The fastening ring is used to fasten the insulating body, the two ends of the pin are fixedly connected by fastening bolts, the nut joint is used to fasten the extruder, the T-shaped mold half is stuck in the groove on the nut joint, and the fastening ring is in the Both ends of the T-shaped half-mold are used to fasten the T-shaped half-mold, so that the T-shaped half-mold clamps the insulating body to achieve a fastened state. Embodiment: First, process the ends of two high-voltage cross-linked cables to be connected, peel off the outer semiconductive layer of each cable head for a length of 120mm, peel off the insulating layer for 100mm, and remove the inner semiconductive layer and the inner winding tape 80mm; Connect the exposed conductor, inner winding tape and semi-conductive layer, and carefully clean the insulating surface of the cable end. Then, buckle the 400mm-long tubular former to the section of cable and clamp it; at the same time, heat the barrel of the plastic extruder, and the temperature of each section from the hopper to the extruder is 70°C, 90°C, and 100°C. , 110 ℃, 130 ℃, put in the same heat-crosslinkable cross-linked polyethylene cable material as the cable insulation body, and start extrusion. When the extruded cable material melt is transparent, control the temperature of the extruder head at 120°C; then, install the tubular former that has clamped the two cable ends to be welded on the extruder head Then, press the uncrosslinked crosslinked polyethylene cable material in the molten state into the middle of the cable end in the molding machine, apply pressure to the melt mechanically, and use the pressure to automatically control The equipment controls the pressure and time, and when the pressure reaches 2.0Mpa, keep it for two minutes; after checking that the injected cable material is full with X-ray, heat the tubular former and its contents to 180°C, keep the temperature constant for 2 hours, and then heat to 250°C , constant temperature for 3 hours, and 130°C for 2 hours; after cooling the tubular former and its contents to room temperature with nitrogen, open the tubular former and take out the connecting cable. Finally, the outer semiconductive layer of the cable is repaired; a 110kV cross-linked cable joint is made. The cross-linked polyethylene fusion cable joint is made of the same material as the cable insulation, extruded on the conductor butt joint at the construction site, and then cross-linked to form an integral body with the cross-linked polyethylene insulation structure of the cable. This method is reliable in quality and structurally compact. In order to prevent the attachment and mixing of impurities, the extruded insulating material needs to be sealed and packaged, and the used molds and pipes need to be cleaned and sealed for storage: use program-controlled temperature adjustment equipment and automatic pressure control equipment to control the temperature, pressure and time of welding and cross-linking .

Claims (6)

1. on-site crosslinked polyethylene cable joint welding technique, it comprises oversheath (1), aluminium sheath (2), outer semiconducting layer (3), insulating body (4), cable conductor (5), tubulose former (6), interior semi-conductive layer (7), dose insulating body (8), dead ring (9), fastening bolt (10), pin (11), screw connector (12), T type half module (13), extruder (14), squeeze note machine (15), it is characterized in that: be to adopt with cable insulation body (4) but the polythene material of identical heat cross-linking, be heated the molten condition more than the softening temperature, enter in the tubulose former (6) from tubulose former (6) side, be evenly distributed on and be fixed, the outer interior semi-conductive layer (7) of two cable conductors (5) of having connected on every side; Be welded together with the insulating body (4) of twisted polyethylene cable end, then under crosslinked temperature and pressure, carry out crosslinkedly, make cable joint.

2. on-site crosslinked polyethylene cable joint welding technique according to claim 1, it is characterized in that: it is to be in uncrosslinked molten condition when interior that crosslinked polyethylene cable joint welding material heating enters tubulose former (6), and its temperature is 120-130 ℃.

3. on-site crosslinked polyethylene cable joint welding technique according to claim 1 is characterized in that: crosslinked polyethylene cable joint welding material heating enters tubulose former (6) and is not less than under the pressure of 2.0MPa when interior.

4. on-site crosslinked polyethylene cable joint welding technique according to claim 1 is characterized in that: the crosslinking temperature after the insulating body of crosslinked polyethylene cable joint welding material melt and cable end (4) is welded together is 180-250 ℃.

5. on-site crosslinked polyethylene cable joint welding technique according to claim 1, it is characterized in that: the manufacturing technology steps of crosslinked polyethylene cable joint welding comprises: the outer semiconducting layer (3) of two cable joint ends that will connect, insulating body (4), interior semi-conductive layer (7) and interior strip winding are peelled off certain-length, connect the cable conductor (5) that has exposed, interior strip winding and interior semi-conductive layer (7), handle and cleaning cable overhang insulation surface, tubulose former (6) is buckled in insulating body (4) goes up and clamp; Again plastics squeeze note machine (15) barrel is heated, drop into cable insulation body (4) but the cross-linked poly-ethylene cable material of identical heat cross-linking, and start squeeze note machine (15) is extruded the cross-linking polyethylene materials of molten, when the CABLE MATERIALS melt of extruding is continuous transparence, squeeze note machine (15) temperature is controlled at 120 ℃ of constant temperature, the tubulose former (6) that clamps two cable ends treating welding is installed on the squeeze note machine (15), tubulose former (6) and T type half module (13) are heated to 120 ℃; Still the uncrosslinked cross-linked poly-ethylene cable material that will be in molten condition is pressed in the tubulose former (6), when reaching 2.0MPa, pressure carries out pressurize, after the CABLE MATERIALS of injecting has been full of, with the pressurization of tubulose former (6) and Dissolve things inside thereof and be heated to 180 ℃, constant temperature 2 hours, be heated to 250 ℃ then, constant temperature 3 hours, 130 ℃ of constant temperature 2 hours, with nitrogen cooling tubulose former (6) and Dissolve things inside thereof to room temperature, open tubulose former (6) and take off, to cable joint is outside do suitably to handle after, repair cable outer semiconducting layer (3).

6. on-site crosslinked polyethylene cable joint welding technique according to claim 5, it is characterized in that: the outer semiconducting layer of every cable socket (3) length is removed 80-200mm, insulating body (4) removes 60-180mm, and interior semi-conductive layer (7) removes 40-160mm.

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